This invention relates to a transport system for magnetic tape recorder and reproducer sets, and particularly for cassette magnetic tape recorders, in which the magnetic tape is driven by means of two capstans.
In order to assure an unobjectionable tape run and a satisfactory contact between the tape and a magnetic recording and reproducing head, the tape should be tensioned and moved with the utmost uniformity past the head. However, the tape reels and tape winding equipment of tape recorders are always subject to inaccuracies of running which cause corresponding fluctuations of the tape tension and thereby deteriorate the constancy of the running properties of the tape and the contact between the latter and the head.
It is known that these drawbacks can be avoided by driving the tape with two capstans, in which case the magnetic head is located between the two capstans. In order to stabilize the synchronized running of the capstans, each of them is provided with a gyratory mass and the capstans are driven in the same sense of rotation by means of a common belt from a single motor.
The reach of the belt from the first to the second gyratory mass undergoes an extension of its length due to the driving moment transmitted thereto, and this tape extension causes the second gyratory mass to run at a lower rpm than the first one. The reach of the magnetic tape transported between the two capstans with the aid of pressure rollers is thereby tensioned in a desired degree. Moreover, this tape reach is not subject to any uneven running of the tape reels or of the winding equipment.
A disadvantage of a known tape transport system resides in the fact that, in order to attain a sufficient constancy of speed in the running of the capstans, the latter must be provided with gyratory masses. However, when reversing the direction of running and when starting or stopping the tape solely by switching off the motor current, the inertia of the gyratory masses affects the switching times disadvantageously.